Ceramics-Silikáty 68, (1) 7 - 13 (2024)

Due to the superior reactivity of the ultrafine structure of metakaolin, the size reduction was endeavored by various techniques. The molten salt process is an interesting method due to its low power consumption and environment benign. In this study, metakaolin was subjected to the molten salt process using NaCl at temperatures of 800°C and 850°C. The crystallization, bonding vibration, and morphology of the processed powders were determined by using the analytical techniques of X-ray diffractogram (XRD), fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM), respectively. The treatment process operated at 850°C exhibits a most intrinsic defect, indicating the internal stress existence. At the consistent condition, FT-IR spectrum at 963 cm^-1 confirms the emerged defect by showing Al incorporation in the asymmetric bonding of Si−O−Si. SEM analysis depicts an exfoliation of flake when heating at 850°C. The findings contribute to the fundamental understanding of the structural characteristics of molten salt-treated metakaolin. This pathway can potentially serve as a size-reducing technique for large-scale production.